Grade 11 Physics Questions

[Raza]

Hello,
Just couple of of Physics questions. I want to make sure I got them right.

1.How much force (tension must a rope withstand if it is used to accelerate a 1700 kg car at 0.50m/s^2 on a frictionless surface.
I got:
(1700)(0.50)

F=850\frac{kgm}{s^2}

2.A 0.15kg baseball travelling at 35.0m/s strikes the catcher's mitt which recoils backwards 10 cm as it brings the ball to rest.
A) What was the force applied by the ball on the glove?
(0.15)(35)
F=5.25\frac{kgm}{s^2}
B) What was the force applied by the glove on the ball?
I don't know how to do this one

3.A parachutist is moving downward with a force due to gravity of 630N experience a a fricitonal air resistence of 450N.
A)Calculate the acceleration of the parachutist.
630-450=180M(Down)
B)Calclation the acceleration of the block.

A=\frac{F}{M}

F=(M)(G)

180=(M)(9.8)

M=\frac{180}{9.8}

M=18.36

A=\frac{180}{18.36}

A=9.8

[vsage]

I don't like the last two. For the third you are right up until F = MG where you for some reason assume the mass is variable with force as opposed to the acceleration. For #2, use the fact that v_f^2 = v_i^2 + 2ad to find the acceleration. From there it's trivial to find the force.

[maverick280857]

I don't like the last two.

What do you mean you don't like them??

Anyway Raza, for question 2(b) you need to know Newton's Third Law: the magntiude force F_{AB} on A due to B equals the magnitude of the force on B due to A, F_{BA} and these forces are equal and opposite:

\vec{F_{AB}} = -\vec{F_{BA}}

Hope that helps.

Cheers
Vivek